Conventionally, there have been invented various kinds of puncture devices for collecting blood from skins of human beings and animals for analysis of the blood. In recent years, a puncture device in which an urging force for puncture is charged simultaneously with attachment of a puncture needle to the puncture device has been invented (refer to Patent Document 1: Japanese Published Patent Application No. 2000-245717). Such puncture device performs operations of puncture and withdrawal using two compression springs, i.e., a first compression spring for puncture and a second compression spring for withdrawal. Further, a puncture needle cartridge for discarding a puncture needle which has touched the skin has been developed to avoid infection due to attached blood.
FIG. 10 is a cross-sectional view of a conventional puncture device 1100. In FIG. 10, a natural position of a plunger 1002 is restricted by the total length of a first compression spring 1000, and the plunger 1002 is urged toward a front end of the puncture device 1100 by a restorative force of the first compression spring 1000 during puncture, while it is urged toward a rear end of the puncture device 1100 by a restorative force of the second compression spring 1001 during withdrawal. A charge lever 1003 slides backward to attach a puncture needle 1004 to the puncture device, and simultaneously, it stores a urging force for puncture by using the first compression spring 1000 and the second compression spring 1001.
FIG. 11 is a cross-sectional view of a conventional puncture needle cartridge 1100. As shown in FIG. 11, the puncture needle cartridge 1101 comprises a puncture needle holder 1005, a lancet body 1007 having a puncture needle 1004, and a puncture needle protection cap 1006 for protecting the puncture needle 1004. The puncture needle holder 1005 houses the lancet body 1007. The lancet body 1007 is stored so as to be movable in the puncture needle holder 1005 along its axial direction. Further, the lancet body 1007 has a large diameter portion 1008 to prevent the lancet body 1007 from moving toward an opening of the puncture needle holder 1005, i.e., toward the front end, unless a predetermined force is applied.
The puncture needle cartridge 1101 constituted as described above is attached to the puncture device 1100, and the lancet body 1007 is inserted in the plunger 1002 of the puncture device 1100. When performing puncture, this plunger 1002 is moved by an urging means, and thereby the lancet body 1007 projects toward the front end and the puncture needle 1004 protrudes from the opening of the puncture needle holder 1005, and thus the puncture site. After the puncture, when the puncture needle 1004 is removed from the puncture site, the lancet body 1007 is moved in a direction opposite to the forward direction (i.e., toward the rear end) by the urging means of the puncture device 1100, and thereby the puncture needle 1004 is again housed in the puncture needle holder 1005.